This proposal seeks funding for electronic dissemination and support of the Integrated Public Use Microdata Series (IPUMS). The IPUMS--the world's largest publicly available demographic database--is a coherent series of individual-level census data drawn from eleven census years between 1850 and 1990. The National Institutes of Health funded the creation of many of the component data files of the IPUMS. Funding for electronic dissemination and user support is essential if the IPUMS is to realize its potential as a vital multi-disciplinary resource. The development of the Internet and World Wide Web (WWW) promises to transform fundamentally the nature of electronic data dissemination. At the same time, the proliferation of fast personal computers and UNIX workstations is already revolutionizing data analysis. This proposal capitalizes on both of these developments by making the largest and most powerful population database readily available for analysis on desktop machines. The research plan can be broken into three tasks: 1. Development of an interactive Java-based extraction system for use on the WWW. Users will be able to fashion subsamples containing only those years, subpopulations, and variables that suit their research interests and computing power. They will also be able to construct new variables that capitalize on the hierarchical structure of the database. 2. Conversion of IPUMS documentation into hypertext format to facilitate navigation. The documentation will be integrated with the extraction system so that researchers can make informed choices in designing their subsamples. By using Adobe Acrobat format, the documentation will be downloadable onto virtually any computer platform while retaining its hypertext functions. 3. Ongoing support for users. Four general areas of need will be the focus: help for users of the extract system, data, and documentation; establishment of a Web site as a clearinghouse for researchers; correction and posting of any errors discovered in the IPUMS; and dissemination efforts to make the academic community aware of this resource.